As the year moves toward its conclusion, we have been listing the most pirated entertainment titles of 2009. Following our Top 10 games and movies charts, we now turn to the most downloaded TV-shows. Despite declining viewership offline, Heroes is the most downloaded show, with over 6 million downloads for a single episode.

TV-shows are gaining popularity on BitTorrent year after year. In 2009 a new milestone was reached; for two shows in the top 10 – Heroes and Dexter – the number of downloads on BitTorrent has exceeded the average viewership on US television.

The rise of unauthorized downloading of TV-shows is a signal that customers want something that is not available through other channels. Availability seems to be the key issue why people turn to BitTorrent, and this is also reflected in the fact that most downloads occur from countries where the show has yet to air on TV.

Outside the US, fans sometimes have to wait for weeks or even months before the show airs on TV in their own country. Many of them are simply not that patient or willing to torture themselves, and turn to BitTorrent in desperation.

Despite massive piracy of TV-shows, there are plenty of opportunities for distributors and broadcasters to win viewers back. The piracy figures simply show that TV viewing habits are changing. There is a huge interest in on-demand TV and there are millions of viewers that can potentially bring in millions of dollars in revenue.

Below we have compiled a list of the most downloaded TV-shows, together with the viewer average for TV in the US, based on data from Nielsen. The data for the top 10 is collected by TorrentFreak from several sources, including reports from all public BitTorrent trackers. All the data is carefully checked and possible inaccuracies are systematically corrected.